Subtitle Overlap Fixer

The Subtitle Overlap Fixer scans the SubRip text you paste into the SRT Content box and reports every cue whose start falls before the previous cue's end, naming the cue number and the exact size of the collision in seconds. With Auto-fix overlaps (shorten later cue) ticked it also returns a corrected SRT beneath the report; left unticked it is a read-only audit.

An overlap means two captions are told to be on screen at the same instant. Depending on the player you get a flicker, a caption that never appears, or two lines stacked and clipped off the safe area. They creep in when cues are merged, when a translator extends a line to fit a longer language, or when timings come from ASR output. Broadcasters and accessibility auditors routinely fail files for it, so subtitlers and QC staff run an overlap check as a final gate before delivery.

The tool walks the cue list in order, comparing each start against the preceding end and reporting the difference in seconds to two decimals. With auto-fix on, the later cue's start is pushed forward to exactly the previous cue's end so the two sit flush; if that new start would meet or pass the cue's own end, the end is nudged to start plus one millisecond so no cue becomes zero-length. Fixing runs sequentially, so cascading overlaps resolve in one pass, and subtitle text is never edited.

All parsing happens in your browser with no upload, and corrected output downloads as a .srt file.

• Exact overlap measurement: Every conflict is reported as a sentence naming both cue numbers and the collision size in seconds to two decimals, so you can tell a three-frame nudge from a two-second structural problem.
• Optional automatic correction: The Auto-fix overlaps (shorten later cue) checkbox decides whether you get a pure report or a report plus a repaired SRT, letting the same tool serve as both an auditor and a fixer.
• Flush-cut repair strategy: Auto-fix moves the later cue's start to the earlier cue's end rather than truncating the earlier line, which preserves the reading time of the caption already on screen.
• Zero-length protection: If pushing a start forward would swallow the cue entirely, its end is extended so the cue always keeps a positive duration and never becomes an invalid block.
• Cascade handling: Cues are processed in order, so a run of consecutive overlaps is untangled in one pass instead of needing repeated runs.
• Text left untouched: Only start and end times are modified; wording, line breaks and any inline markup in your captions come through exactly as written.
• Clean pass confirmation: When nothing overlaps you get an explicit all-clear rather than empty output, which is what you want to paste into a QC sign-off.
• Private and instant: The check runs locally in the browser with no upload and no waiting on a server round trip.

1. Paste the captions you want to check into the SRT Content box, or click Load sample to try it on a file that deliberately contains an overlap.
2. Decide what you need from this run and leave Auto-fix overlaps (shorten later cue) unticked for a report-only audit, or tick it when you want the corrected file as well.
3. Press Run and read the report at the top of the output, which either confirms no overlapping cues or lists each conflict with its cue numbers and size in seconds.
4. Look up any large overlap in your subtitle editor before accepting a fix, since a multi-second collision usually means a cue is mistimed rather than merely tight.
5. If auto-fix was on, scroll past the report to the fixed SRT section and spot-check the cues that were mentioned to confirm the new timings read naturally.
6. Copy the corrected text or download it as a .srt file, then re-run the tool on that output to confirm it now reports a clean pass.

Example 1 - a tight collision from a merged line. Cue 2 was extended during translation and now begins before cue 1 has left the screen.

Before:
1
00:00:01,000 --> 00:00:04,000
We were nearly out of fuel.

2
00:00:03,000 --> 00:00:06,000
And the radio had gone dead.

Report: Cue 2 overlaps cue 1 by 1.00s.

After (auto-fix on):
2
00:00:04,000 --> 00:00:06,000
And the radio had gone dead.

Example 2 - report only, before a delivery. With the checkbox cleared you get just the audit line, which is enough to prove the file passes a platform spec that forbids simultaneous cues.

No overlapping cues.

In the first case the later cue simply starts where the earlier one ends, so both lines still display in full and neither flickers.

• Avoids rejected deliveries: Overlapping cues are a standard automatic fail on broadcast and streaming QC, and catching them yourself is far cheaper than a redelivery cycle.
• Stops captions disappearing on viewers: Many players simply drop one of two colliding cues, so fixing overlaps means the audience actually reads every line you wrote.
• Turns a tedious manual sweep into one click: Finding collisions by eye in a thousand-cue file is hours of scrolling; the report pinpoints them in seconds.
• Keeps you in control of the edit: The report-only mode lets you review conflicts and decide which deserve a hand fix before you let anything be changed automatically.
• Supports accessibility compliance: Reliable, non-colliding captions are part of delivering usable access for deaf and hard-of-hearing viewers rather than just ticking a box.
• Nothing leaves your machine: Pre-broadcast scripts stay confidential because the whole check happens in your browser.